Rivers, lakes, streams, drinking water supplies, swimming pools, shower rooms, industrial water systems, and the like, are frequently polluted by the excessive growth of algae and other microorganisms which impart a distasteful appearance and odor to the water and generally interfere with the flow of the water and may be harmful to health.
Copper ions are known to be effective against the growth of algae. In the past water-soluble copper compounds, such as copper sulfate, have been used extensively as algaecides. Copper ions released by copper sulfate when added to water, react with carbonates or bicarbonates found in water to produce insoluble copper compounds which precipitate and cause turbidity or cloudiness in the treated water. If excessive amounts of insoluble copper compounds settle out, the compounds can form a sludge or deposit, which in the case of a lake or stream, may tend to destroy the fish life or zooplankton which is essential as fish food.
To overcome the problems associated with the use of copper sulfate, a complex formed by the reaction of copper sulfate and an alkanolamine, as disclosed in U.S. Pat. No. 2,734,028, has been used and has achieved wide success as an algaecide. A complex of this type has the ability to maintain the copper ions in solution, even when the algaecide is added to alkaline water containing high proportions of carbonates or bicarbonates, as well as soft water situations.
The copper alkanolamine complex of the type disclosed in U.S. Pat. No. 2,734,028 is normally packaged as a concentrated aqueous solution in glass, plastic or metal containers and is apt to be stored for extended periods. It has been found that when this complex is stored over long periods of time, and particularly when the containers may be subjected to sunlight and/or warm temperatures, decomposition of the complex occurs, resulting in a precipitation of copper. Precipitation of the copper removes the toxic copper ions from the solution and thus decreases the effectiveness of the complex when subsequently diluted and added to the water to be treated.
The copper complex prepared from copper sulfate has a further disadvantage in that the sulfate ions tend to combine with hydrogen in the aqueous solution to form sulfuric acid, which is highly corrosive, thereby presenting problems in handling, shipment and storage of the concentrated product.
The presence of the sulfate ions has a further disadvantage in that when the complex is added to the water to be treated in the recommended dosage, a sulfate content results of approximately 0.5 ppm per acre foot of water being treated. This high concentration of sulfates can be conducive to diatom blooms. Diatom requires sulphates for the uptake of silica for the cell walls. Furthermore, when copper sulphate is used as the starting material in forming the complex, the concentration of toxic copper ions is limited in the concentrated product, with a concentration of approximately 7% being the upper limit.
To avoid problems associated with the use of copper sulfate, attempts have been made in the past to utilize other copper-containing materials, such as copper carbonate as an algaecide, as disclosed in U.S. Pat. No. 3,634,061. Copper carbonate is relatively insoluble in water and large amounts of this material have to be used to obtain minimum algae control. Not only is this procedure costly, but the undissolved copper carbonate remains ineffectual as an algaecide in the aquatic environment and remains on the bottom of the body of water and can be toxic to fish and fish food organisms.